Information Technology Reference
In-Depth Information
Fig. 5.1 Scheme of a reaction-diffusion processor
5.1.1
Input of Information
For entering data into a reaction-diffusion medium, a “macro-micro” interface is
required. It converts the input information (a spatial distribution of physical
stimuli) into the corresponding spatial distribution of molecular components of
the medium. Particularly convenient for entering information are photosensitive
media. In this case, the information being entered represents an image (generally,
an arbitrary distribution of light intensity), projected by an optical system on the
surface of the layer or into the volume of the medium. The medium itself contains
a photosensitive catalyst of the Belousov-Zhabotinsky reaction initiating a
sequence of photochemical reactions that lead to a change in the content of its
basic components:
Ru
þ
2
ν!
Ru
þ
2
,
þ
h
Ru
þ
2
þ
C
3
H
3
BrO
4
!
Ru
þ
3
þ
Br
þ
organic products,
Ru
þ
3
þ
C
3
H
3
BrO
4
!
Ru
þ
2
þ
Br
þ
organic products
:
As a result, at each point of the medium changes of the concentrations of its
components take place that depend on the intensity of light emission at this point.
In other words, a chemical implementation of the input image appears in the
medium.
Before the source data for solving the selected task are input into the medium, it
should be reset to some initial form not containing significant information. For this
purpose it is convenient to illuminate the medium by intense light emission. Let us
consider this process in more detail and turn again to the zero isoclines of the
photosensitive Belousov-Zhabotinsky medium (Fig.
5.2
). The analytical expres-
sion for an S-shaped isocline includes a parameter describing the effect of light
radiation on the dynamics of the medium (see previous chapter). It is easy to see
that this stimulus leads to a shift of the S-shaped isocline along the axis of ordinates.
